A. Field of the Invention
The present invention relates to systems for locking a wheel to a frame and, in particular, to a locking system for locking a wheel onto a wheelchair
B. Related Art
A typical wheelchair includes a frame onto which front and rear wheelchair wheels attach. In older wheelchair designs, the wheels have been fixedly attached to the wheelchair frame, and tools such as wrenches have been required to remove the wheel from the frame. More recent designs include a quick-release mechanism to permit convenient removal of the wheel from the frame.
One quick release design provides the user with a button on the outside of the wheel. To release the wheel from the frame, the user pushes the button to release a lock. While the user depresses the button, he or she can pull the wheel from the frame.
A problem with the push-and-remove type of wheel is that wheelchairs often bump into walls and other objects during use. It is possible for the button to be pushed inadvertently by, for example, the wheel bumping into a wall. The wheel can then become disengaged from the chair by accident.
The present invention relates to a wheelchair locking system that reduces the likelihood that a wheel will accidentally disengage from the wheelchair.
In one embodiment of the invention, a multi-stage wheel lock is provided. In a first locked position, the wheel is fully locked to the wheelchair frame. In a second locked position, the wheel is moved from the initial locked position, but remains locked to the wheelchair frame. The wheel may have two, three or more locked positions.
In another embodiment of the invention, a wheelchair wheel has an axle. The axle is provided with a ball bearing lock. The axle extends through an axle receptor associated with the wheelchair frame. The ball bearings engage with or against a portion of the axle receptor. When the ball bearing lock is initially released, the axle may be partially removed from the axle receptor. However, the ball bearings again engage with a portion of the axle receptor to lock the wheel onto the wheelchair frame in a second locked position. When the ball bearing lock is again released, the axle may be disengaged from the axle receptor entirely.
In another embodiment of the invention, the wheelchair wheel has an axle that is provided with a quick release lock with a push button release. In the initial locked position, the axle is fully locked to the wheelchair frame. If the push button release is pushed briefly, the axle may partially disengage from the frame, but locks into a second locked position before becoming fully disengaged from the frame. The push button must be pushed again to disengage the axle from the second locked position. This two-stage lock prevents accidental disengagement of the wheel when, for example, the wheel bumps up against a wall or other surface. In a further embodiment, the user may release the axle from the initial locked position without the axle become locked in the second locked position by continuing to push the release button as the wheel is being removed from the wheelchair.
These and other aspects of the invention will become apparent from a review of the specification, drawings and claims.